In internal combustion engines, mixers of the aforementioned type may be used in their exhaust system, for example, if a gas or a liquid is to be admixed with the exhaust gas. The mixing should be especially intense so as to be able to produce the most homogeneous possible gas mixture and/or to achieve effective evaporation of the liquid introduced and to achieve thorough mixing of the vaporized liquid with the exhaust gas. At the same time, the mixer should not produce an excessively great pressure increase in the exhaust system. Since static mixers work with deflection of flow, they necessarily result in a certain increase in pressure. Therefore, there has been a demand for effective mixers that have only a comparatively low flow resistance. Furthermore, another factor to be taken into account for applications in motor vehicles is that usually there is only a small installation space for accommodating such a mixer in the exhaust systems used there.
In the prior art, EP 1 371 824 A1 discloses that mixing elements may be arranged in an exhaust channel of an exhaust system with the help of which a reactant that is used for selective catalytic reduction of nitrogen oxides in a downstream SCR catalytic converter may be mixed with the exhaust gas. The mixing elements may be designed as baffle elements.
Prior art reference DE 197 41 199 A1 discloses that an expanded metal mesh may be used as a static mixer in a flow channel of an exhaust gas purification system, so that an extremely short mixing zone can be achieved.
Reference DE 43 13 393 A1 discloses another static mixer which may be used upstream from a DeNOx catalyst of an exhaust system. The known mixer has a frame structure arranged in an exhaust-carrying channel of the exhaust system and having several carriers running across the direction of flow, several planar trapezoidal baffles of the carriers protruding into and across the flow direction.
Reference DE 41 09 305 A1 discloses a device for introducing a reactant into a gas stream having multiple outlet openings through which the reactant emerges in the opposite direction from the flow. Each outlet opening is assigned a mixing element on the outgoing flow side to create turbulence in the reactant with the exhaust stream.